Shuttle Discovery's Gas Leaks Repaired In Time for Wednesday Launch

The space shuttle Discovery and its STS-133 crew will deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the International Space Station. The launch attempt on Wed., Nov. 3 was delayed, however.Credit: NASA/Troy Cryder

CAPE CANAVERAL, Fla. ? NASA is counting down toward the
final flight of space shuttle Discovery after engineers successfully repaired
two minor gas leaks on the spacecraft in time for one last launch on Wednesday
(Nov. 3).

Discovery's final launch has been delayed two days due to leaky
helium and nitrogen seals found in the shuttle's right orbital maneuvering
system pod last week.

Technicians raced to troubleshoot the problem and
re-pressurize the orbiter's rocket engine in time for a targeted launch at 3:52
p.m. EDT (1952 GMT) on Wednesday. The official countdown toward liftoff began
today (Oct. 31) at 2 p.m. EDT (1800 GMT).

"Work is on schedule," NASA test director Steve
Payne told reporters in a status briefing this morning. "We completed
flight pressurization ? all went well. That is behind us now."

Part of those repairs included replacing a valve on
Discovery that had never been touched since the shuttle was built in the early
1980s, Payne said. [Gallery:
Building Space Shuttle Discovery]

The weather forecast for Wednesday's launch calls for a 70
percent chance of acceptable conditions at the launch site, according to Kathy
Winters, NASA's shuttle weather officer. The only major weather threats for
launch are low clouds and a chance of isolated showers near the launch pad.

On its 11-day mission, Discovery will haul critical spare
parts to the space station, including a storage room and a humanoid
robot to assist the crew of the orbiting laboratory.

Discovery's
final flight will be NASA's 133rd shuttle mission, before the space agency
brings its 30-year space shuttle program to a close in 2011.

"She's been an incredible
vehicle," Payne said. "She's always amazed us with everything she
can do, and we expect this flight will be no different."

NASA will retire the three remaining shuttles in its fleet ?
Discovery, Atlantis and Endeavour ? next year to make way for a new plan aimed
at sending astronauts to visit an asteroid and Mars. Discovery is the oldest of
NASA's space shuttles.

While the weather outlook for Wednesday looks promising,
NASA is tracking some other storms that could stall Discovery's flight if it
suffers another launch delay.

A weather front pushing down into parts of central Florida
that could cause concerns if Discovery's launch is stalled another 24 hours or
more, Winters said.

This incoming weather system could prohibit launch due to
showers and even thunderstorms in the area, Winters said. Under these
circumstances, forecasts currently estimate a 60 percent chance of favorable
conditions if NASA officials were to delay the launch by 24 hours.

NASA has until Sunday, Nov. 7 to launch Discovery toward the
International Space Station launch within the current window. After that, the
space agency would have to wait until early December to try again.